docs(Number): add info about when to use and not to use (#2955)

Co-authored-by: Anders <[email protected]>

packages/dnb-design-system-portal/src/docs/uilib/extensions/forms/base-fields/Number/info.mdx

@@ -8,6 +8,16 @@ showTabs: true
 
 There is a corresponding [Value.Number](/uilib/extensions/forms/create-component/Value/Number) component.
 
+## When to use and not to use
+
+`Field.Number` only allows the user to enter numbers (negative and positive) and decimal numbers.
+
+If a number has the type of number, and can not start with a zero, this field may be considered.
+
+But for e.g. a customer number, you rather use [Field.String](/uilib/extensions/forms/base-fields/String/).
+
+Internally, it is used by e.g. [Field.Currency](/uilib/extensions/forms/feature-fields/Currency/).
+
 ## Autocomplete and autofill
 
 Check out the [Field.String](/uilib/extensions/forms/base-fields/String/#autocomplete-and-autofill) docs about autocomplete.